1. Field of the Invention
The present invention relates to a toner for developing electrostatic latent images in image forming processes such as electrophotography and electrostatic printing, or a toner for forming toner images in an image forming process of a toner jet system.
2. Description of the Related Art
In recent years, on account of requirements for making printers and copying machines more high-speed, more highly stable and much more compact, it is sought to reduce the number of articles of component parts as individual component parts are made more high-function. In order to attain a stable image density in electrophotographic systems, it is necessary to set up development conditions that are always stable in a development process. However, where a toner has an unstable charge quantity, a high load may be applied to a system for controlling the developing performance, such that development bias conditions and so forth must be made proper every time, and this may often make apparatus large in size and result in a high production cost. In order to lessen such a load, the toner is required to be improved in the stability of its charge quantity, in particular, the stability of charging against any changes in temperature and humidity.
Proposals to improve such environmental stability of charge quantity of toner have been made in a large number. Of these, it is prevailing to control it by the aid of a charge control agent, and proposed are a toner containing a carixarene compound, one making use of an iron-containing azo dye and one making use of an organic boron compound (e.g., Japanese Patent Applications Laid-open No. H07-152207, No. H08-006297, No. 2002-287429, No. 2004-219507).
However, such toners as above are still unsatisfactory for the charge quantity of toner and charging rise performance thereof that are concerned in any changes in temperature and humidity environmental factors surrounding the toners. It has come about that image density comes to change during printing and, especially in a high-temperature and high-humidity environment, difficulties such as image fog occur with any non-uniformity of charge quantity distribution.